End-of-life decline of cognitive functions are correlated

(HealthDay News) -- In the last years of life, cognitive abilities decline rapidly, with a strong correlation between different functions; and cognitive activity is associated with cognitive function and predictive of cognitive decline, according to two studies published online April 4 in Neurology.

Robert S. Wilson, Ph.D., from the Rush University Medical Center in Chicago, and colleagues conducted a longitudinal clinical-pathologic cohort study of 174 older individuals without dementia at baseline. Participants completed a battery of cognitive performance tests at annual intervals for six to 15 years prior to death. The researchers found that cognitive decline was relatively gradual before the terminal period, with the rates of change in different cognitive domains moderately correlated, ranging from 0.25 to 0.46. During the terminal period, cognitive decline was rapid, with a strong correlation between the rates of change in different functions, ranging from 0.83 to 0.89.

In a second study, Wilson and colleagues conducted annual clinical evaluations for 1,076 older persons without dementia at baseline to investigate whether late-life participation in mentally stimulating activities affects cognitive health. Evaluations included self-report of participation in mentally-stimulating activities as well as a battery of cognitive performance tests. During a mean observation period of 4.9 years, the researchers found that there was a moderate correlation in the decline in rates of cognitive activity participation and cognitive functioning. In a given year, the level of cognitive activity predicted global cognitive function in the following year, but the association was unidirectional.

"The results suggest that more frequent mental stimulation in old age leads to better cognitive functioning," the authors of the second study write.

Several authors of both studies disclosed financial ties to the pharmaceutical and nutrition industries. One of the authors disclosed ties to Pain Therapeutics; another author disclosed ties to Vigorous Minds.